Method for stiffening a curved sheet-metal panel by means of a cardboard panel

Abstract

A method for stiffening a curved sheet-metal panel, in which a flat cardboard panel is applied to the concave face of the curved sheet-metal panel, includes a step in which a number of parallel cuts that pass partially through the thickness of the cardboard panel are made in that face of the cardboard panel that is intended to be applied to the concave face of the sheet-metal panel. A number of adhesive strips that each cover said parallel cuts are applied to said face of the cardboard panel and said face, provided with said adhesive strips, of the cardboard panel is applied to said concave face of the sheet-metal panel.

Claims

1. A method for stiffening a curved sheet-metal panel in which a flat cardboard panel is applied on a concave face of the curved sheet-metal panel, wherein: (a) a series of parallel cuts that pass partially through the thickness of the cardboard panel is made in a face of the cardboard panel that is intended to be applied to the concave face of the sheet-metal panel, (b) a series of elastic adhesive strips respectively covering said parallel cuts is applied to said face of the cardboard panel; and (c) said face of the cardboard panel provided with adhesive strips is applied on said concave face of the sheet-metal panel.

2. The method according to claim 1, wherein the adhesive strips are centered on the respective cuts.

3. The method according to claim 1, wherein the cardboard panel comprises three parallel sheets separated from one another by a corrugated sheet, the cuts passing through two of said parallel sheets as well as the corrugated sheet comprised between them.

4. The method according to claim 1, wherein: (a) the sheet-metal panel is substantially rectangular and concave in the direction of its length and in the direction of its width; and (b) two series of cuts are made on said face of the cardboard panel intended to be applied on the concave face of the cardboard panel, one of the series being oriented in the direction of the length of the panel and the other being oriented in the direction of the width of this panel.

5. The method according to claim 4, wherein only the series of cuts made in one of the two directions is covered by adhesive strips.

6. The method according to claim 5, wherein the series of cuts covered by adhesive strips is the series of cuts oriented in the direction of the length of the cardboard panel.

7. The method according to claim 1, wherein step c) of the method is carried out by placing the cardboard panel provided with said adhesive strips flat in a basin whereof the peripheral edge is applied tightly against the concave face of the sheet-metal panel, and creating a vacuum in the basin sufficient for the cardboard panel to press against the sheet-metal panel and to adhere thereto using the adhesive strips.

8. A stiffening panel for a curved sheet-metal panel, said stiffening panel comprising a cardboard panel configured to be applied on a concave face of the curved sheet-metal panel, wherein the stiffening panel further comprises a series of parallel cuts passing partially through the thickness of the cardboard panel from an upper face of the cardboard panel and a series of elastic adhesive strips respectively covering said parallel cuts.

9. The stiffening panel according to claim 8, wherein the adhesive strips are centered on the respective cuts.

10. The stiffening panel according to claim 8, wherein the cardboard panel comprises three parallel sheets separated from one another by a corrugated sheet, the cuts passing through two parallel sheets as well as the corrugated sheet being comprised between them.

Description

(1) In the appended figures, provided as non-limiting examples:

(2) FIG. 1 is a partial perspective view of the body of a motor vehicle;

(3) FIG. 2 is a cross-section of the cardboard used to stiffen the roof of a motor vehicle showing the first step of the method according to the present disclosure,

(4) FIG. 3 is a view similar to FIG. 2 showing a subsequent step of the method according to the present disclosure,

(5) FIG. 4 is a top view of the cardboard shown in FIG. 3; and

(6) FIG. 5 is a sectional view similar to FIG. 3 showing the cardboard positioned below the roof of a motor vehicle.

(7) FIGS. 2 and 3 show a sectional view of the cardboard panel 7 before it is applied on the concave inner face of the sheet-metal roof 1 of a motor vehicle.

(8) As shown in FIG. 2, in a first step of the method according to the invention, a series of parallel cuts 8 passing partially through the thickness of the cardboard panel 7 is produced on the face 7a of the cardboard panel 7 that is intended to be applied on the concave inner face of the sheet-metal roof 1.

(9) In a following step, shown in FIGS. 3 and 4, a series of adhesive strips 9 respectively covering the parallel cuts 8 is applied on the face 7a of the cardboard panel 7.

(10) These adhesive strips 9 are preferably centered on the cuts 8 (see FIG. 4).

(11) The face 7a of the cardboard panel provided with the adhesive strips 9 is then applied (see FIG. 5) on the concave inner face 1a of the sheet-metal roof 1.

(12) In the example illustrated by FIGS. 2, 3 and 5, the cardboard panel 7 comprises three parallel sheets 10, 11, 12 separated from one another by a corrugated sheet 13, 14.

(13) Furthermore, the cuts 8 pass through two parallel sheets, i.e., the sheets 10, 11, as well as the corrugated sheet 13 comprised between them.

(14) The sheet-metal panel 1 of a motor vehicle is substantially rectangular and is concave in the direction of its length and in the direction of its width.

(15) In this case, two series of cuts 8 and 8a are made on the face 7a of the cardboard panel 7.

(16) The series of cuts 8 is oriented in the direction of the length of the panel 7, and the other series of cuts 8a is oriented in the direction of the width of this panel 7, as shown in FIG. 4.

(17) In this example, only the series of cuts 8 made in one of the two directions is covered by adhesive strips 9.

(18) Furthermore, the series of cuts 8 covered by the adhesive strips 9 is the series of cuts oriented in the direction of the length of the cardboard panel 7.

(19) The step of the method, as illustrated in FIG. 5, is preferably carried out by placing the cardboard panel 7 provided with adhesive strips 9 flat in a basin (not shown) whereof the peripheral edge is applied tightly against the concave face 1a of the sheet-metal roof 1 and creating, in the basin, a sufficient vacuum for the cardboard panel 7 to be applied against the sheet-metal roof 1 and to adhere thereto owing to the adhesive strips 9.

(20) FIG. 5 shows that during this step, the cardboard panel 7 marries the concave surface of the roof 1 owing to the cuts 8 and 8a.

(21) This FIG. 5 in fact shows that the cuts 8 can open due to the concavity of the roof due to the elasticity of the adhesive strips 9, which flatten between the roof 1 and the cardboard panel due to the forces involved.

(22) Thus, the application of the cardboard panel 7 does not exert any excessive force on the roof 1, and the latter does not undergo any damage during implementation of the method according to the invention.

(23) Of course, the invention is not limited to stiffening sheet-metal roofs of motor vehicles, but may apply to the stiffening of any curved sheet-metal panel.